Method of operating a safety vacuum release system

ABSTRACT

Embodiments of the invention provide a method of operating a safety vacuum release system (SVRS) with a controller for a pump including a motor. The method can include measuring an actual power consumption of the motor necessary to pump water and overcome losses. The method can include triggering the SVRS when a dynamic suction blockage is identified in order to shut down the pump substantially immediately. The SVRS can also be triggered when a dead head condition is identified based on the actual power consumption.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 12/572,774filed on Oct. 2, 2009 now U.S. Pat. No. 8,313,306, which claims priorityunder 35 U.S.C. §119 to U.S. Provisional Patent Application No.61/102,935 filed on Oct. 6, 2008, the entire contents of which areincorporated herein by reference.

BACKGROUND

Pool pumps are used to move water in one or more aquatic applications,such as pools, spas, and water features. The aquatic applicationsinclude one or more water inlets and one or more water outlets. Thewater outlets are connected to an inlet of the pool pump. The pool pumpgenerally propels the water though a filter and back into the aquaticapplications though the water inlets. For large pools, the pool pumpmust provide high flow rates in order to effectively filter the entirevolume of pool water. These high flow rates can result in highvelocities in the piping system connecting the water outlets and thepool pump. If a portion of the piping system is obstructed or blocked,this can result in a high suction force near the water outlets of theaquatic applications. As a result, foreign objects can be trappedagainst the water outlets, which are often covered by grates in thebottom or sides of the pool. Systems have been developed to try toquickly shut down the pool pump when a foreign object is obstructing thewater outlets of the aquatic applications. However, these systems oftenresult in nuisance tripping (i.e., the pool pump is shut down too oftenwhen there are no actual obstructions).

SUMMARY

Some embodiments of the invention provide a method of operating a safetyvacuum release system (SVRS) with a controller for a pump including amotor. The method can include measuring an actual power consumption ofthe motor necessary to pump water and overcome losses, calculating anabsolute power variation based on the actual power consumption, andincrementing a dynamic counter value if the absolute power variation isnegative. The method can also include calculating a relative powervariation based on the actual power consumption and identifying adynamic suction blockage if the dynamic counter exceeds a dynamiccounter threshold value and/or the relative power variation is below anegative threshold. The method can further include triggering the SVRSwhen the dynamic suction blockage is identified in order to shut downthe pump substantially immediately.

Some embodiments of the invention provide a method including filteringthe actual power consumption with a fast low-pass filter to obtain acurrent power consumption and incrementing an absolute counter value ifthe actual power consumption and/or the current power consumption aregreater than a threshold power curve. The method can also includeidentifying a dead head condition if the absolute counter value exceedsan absolute counter threshold value and triggering the suction vacuumrelease system when the dead head condition is identified in order toshut down the pump substantially immediately.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pool pump according to one embodimentof the invention.

FIG. 2 is an exploded perspective view of the pool pump of FIG. 1.

FIG. 3A is a front view of an on-board controller according to oneembodiment of the invention.

FIG. 3B is a perspective view of an external controller according to oneembodiment, of the invention.

FIG. 4 is a flow chart of settings of the on-board controller of FIG. 3Aand/or the external controller of FIG. 3B according to one embodiment ofthe invention.

FIG. 5A is a graph of an absolute power variation of the pool pump whena clogged suction pipe occurs at a certain time.

FIG. 5B is a graph of a relative power variation of the pool pump when aclogged suction pipe or water outlet occurs at a certain time.

FIG. 5C is a graph of a relative counter for the relative powervariation of FIG. 5B.

FIG. 6 is a graph of a power consumption versus the speed of the poolpump according to one embodiment of the invention.

FIG. 7 is a schematic illustration of a pool system with a personblocking a water outlet of the pool.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the invention. Various modificationsto the illustrated embodiments will be readily apparent to those skilledin the art, and the generic principles herein can be applied to otherembodiments and applications without departing from embodiments of theinvention. Thus, embodiments of the invention are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope ofembodiments of the invention. Skilled artisans will recognize theexamples provided herein have many useful alternatives and fall withinthe scope of embodiments of the invention.

FIG. 1 illustrates a pool pump 10 according to one embodiment of theinvention. The pool pump 10 can be used for any suitable aquaticapplication, such as pools, spas, and water features. The pool pump 10can include a housing 12, a motor 14, and an on-board controller 16. Insome embodiments, the motor 14 can be a variable speed motor. In oneembodiment, the motor 14 can be driven at four or more different speeds.The housing 12 can include an inlet 18, an outlet 20, a basket 22, a lid24, and a stand 26. The stand 26 can support the motor 14 and can beused to mount the pool pump 10 on a suitable surface (not shown).

In some embodiments, the on-board controller 16 can be enclosed in acase 28. The case 28 can include a field wiring compartment 30 and acover 32. The cover 32 can be opened and closed to allow access to theon-board controller 16 and protect it from moisture, dust, and otherenvironmental influences. The case 28 can be mounted on the motor 14. Insome embodiments, the field wiring compartment 30 can include a powersupply to provide power to the motor 14 and the on-board controller 16.

FIG. 2 illustrates the internal components of the pool pump 10 accordingto one embodiment of the invention. The pool pump 10 can include sealplate 34, an impeller 36, a gasket 38, a diffuser 40, and a strainer 42.The strainer 42 can be inserted into the basket 22 and can be secured bythe lid 24. In some embodiments, the lid 24 can include a cap 44, anO-ring 46, and a nut 48. The cap 44 and the O-ring 46 can be coupled tothe basket 22 by screwing the nut 48 onto the basket 22. The O-ring 46can seal the connection between the basket 22 and the lid 24. An inlet52 of the diffuser 40 can be fluidly sealed to the basket 22 with a seal50. In some embodiments, the diffuser 40 can enclose the impeller 36. Anoutlet 54 of the diffuser 40 can be fluidly sealed to the seal plate 34.The seal plate 34 can be sealed to the housing 12 with the gasket 38.The motor 14 can include a shaft 56, which can be coupled to theimpeller 36. The motor 14 can rotate the impeller 36, drawing fluid fromthe inlet 18 through the strainer 42 and the diffuser 40 to the outlet20.

In some embodiments, the motor 14 can include a coupling 58 to connectto the on-board controller 16. In some embodiments, the on-boardcontroller 16 can automatically operate the pool pump 10 according to atleast one schedule. If two or more schedules are programmed into theon-board controller 16, the schedule running the pool pump 10 at thehighest speed can have priority over the remaining schedules. In someembodiments, the on-board controller 16 can allow a manual operation ofthe pool pump 10. If the pool pump 10 is manually operated and isoverlapping a scheduled run, the scheduled run can have priority overthe manual operation independent of the speed of the pool pump 10. Insome embodiments, the on-board controller 16 can include a manualoverride. The manual override can interrupt the scheduled and/or manualoperation of the pool pump 10 to allow for, e.g., cleaning andmaintenance procedures. In some embodiments, the on-board controller 16can monitor the operation of the pool pump 10 and can indicate abnormalconditions of the pool pump 10.

FIG. 3A illustrates a user interface 60 for the on-board controller 16according to one embodiment of the invention. The user interface 60 caninclude a display 62, at least one speed button 64, navigation buttons66, a start-stop button 68, a reset button 70, a manual override button72, and a “quick clean” button 74. The manual override button 72 canalso be called “time out” button. In some embodiments, the navigationbuttons 66 can include a menu button 76, a select button 78, an escapebutton 80, an up-arrow button 82, a down-arrow button 84, a left-arrowbutton 86, a right-arrow button 88, and an enter button 90. Thenavigation buttons 66 and the speed buttons 64 can be used to program aschedule into the on-board controller 16. In some embodiments, thedisplay 62 can include a lower section 92 to display information about aparameter and an upper section 94 to display a value associated withthat parameter. In some embodiments, the user interface 60 can includelight emitting diodes (LEDs) 96 to indicate normal operation and/or adetected error of the pool pump 10.

The on-board controller 16 operates the motor 14 to provide a safetyvacuum release system (SVRS) for the aquatic applications. If theon-board controller 16 detects an obstructed inlet 18, the on-boardcontroller 16 can quickly shutdown the pool pump 10. In someembodiments, the on-board controller 16 can detect the obstructed inlet18 based only on measurements and calculations related to the powerconsumption of the motor 14 (e.g., the power needed to rotate the motorshaft 56). In some embodiments, the on-board controller 16 can detectthe obstructed inlet 18 without any additional inputs (e.g., withoutpressure, flow rate of the pumped fluid, speed or torque of the motor14).

FIG. 3B illustrates an external controller 98 for the pool pump 10according to one embodiment of the invention. The external controller 98can communicate with the on-board controller 16. The external controller98 can control the pool pump 10 in substantially the same way as theon-board controller 16. The external controller 98 can be used tooperate the pool pump 10 and/or program the on-board controller 16, ifthe pool pump 10 is installed in a location where the user interface 60is not conveniently accessible.

FIG. 4 illustrates a menu 100 for the on-board controller 16 accordingto one embodiment of the invention. In some embodiments, the menu 100can be used to program various features of the on-board controller 16.In some embodiments, the menu 100 can include a hierarchy of categories102, parameters 104, and values 106. From a main screen 108, an operatorcan, in some embodiments, enter the menu 100 by pressing the menu button76. The operator can scroll through the categories 102 using theup-arrow button 82 and the down-arrow button 84. In some embodiments,the categories 102 can include settings 110, speed 112, external control114, features 116, priming 118, and anti freeze 120. In someembodiments, the operator can enter a category 102 by pressing theselect button 78. The operator can scroll through the parameters 104within a specific category 102 using the up-arrow button 82 and thedown-arrow button 84. The operator can select a parameter 104 bypressing the select button 78 and can adjust the value 106 of theparameter 104 with the up-arrow button 82 and the down-arrow button 84.In some embodiments, the value 106 can be adjusted by a specificincrement or the user can select from a list of options. The user cansave the value 106 by pressing the enter button 90. By pressing theescape button 80, the user can exit the menu 100 without saving anychanges.

In some embodiments, the settings category 110 can include a timesetting 122, a minimum speed setting 124, a maximum speed setting 126,and a SVRS automatic restart setting 128. The time setting 122 can beused to run the pool pump 10 on a particular schedule. The minimum speedsetting 124 and the maximum speed setting 126 can be adjusted accordingto the volume of the aquatic applications. An installer of the pool pump10 can provide the minimum speed setting 124 and the maximum speedsetting 126. The on-board controller 16 can automatically prevent theminimum speed setting 124 from being higher than the maximum speedsetting 126. The pool pump 10 will not operate outside of these speedsin order to protect flow-dependent devices with minimum speeds andpressure-sensitive devices (e.g., filters) with maximum speeds. The SVRSautomatic restart setting 128 can provide a time period before theon-board controller 16 will resume normal operation of the pool pump 10after an obstructed inlet 18 has been detected and the pool pump 10 hasbeen stopped. In some embodiments, there can be two minimum speedsettings—one for dead head detection (higher speed) and one for dynamicdetection (lower speed).

In some embodiments, the speed category 112 can be used to input datafor running the pool pump 10 manually and/or automatically. In someembodiments, the on-board controller 16 can store a number of manualspeeds 130 and a number of scheduled runs 132. In some embodiments, themanual speeds 130 can be programmed into the on-board controller 16using the up-arrow button 82, the down-arrow button 84 and the enterbutton 90. Once programmed, the manual speeds 130 can be accessed bypressing one of the speed buttons 64 on the user interface 60. Thescheduled runs 132 can be programmed into the on-board controller 16using the up-arrow button 82, the down-arrow button 84, and the enterbutton 90. For the scheduled runs 132, a speed, a start time, and a stoptime can be programmed. In some embodiments, the scheduled runs 132 canbe programmed using a speed, a start time, and a duration. In someembodiments, the pool pump 10 can be programmed to run continuously.

The external control category 114 can include various programs 134. Theprograms 134 can be accessed by the external controller 98. The quantityof programs 134 can be equal to the number of scheduled runs 132.

The features category 116 can be used to program a manual override. Insome embodiments, the parameters can include a “quick clean” program 136and a “time out” program 138. The “quick clean” program 136 can includea speed setting 140 and a duration setting 142. The “quick clean”program 136 can be selected by pressing the “quick clean” button 74located on the user interface 60. When pressed, the “quick clean”program 136 can have priority over the scheduled and/or manual operationof the pool pump 10. After the pool pump 10 has been operated for thetime period of the duration setting 142, the pool pump 10 can resume tothe scheduled and/or manual operation. If the SVRS has been previouslytriggered and the time period for the SVRS automatic restart 128 has notyet elapsed, the “quick clean” program 136 may not be initiated by theon-board controller 16. The “time out” program 138 can interrupt theoperation of the pool pump 10 for a certain amount of time, which can beprogrammed into the on-board controller 16. The “time out” program 138can be selected by pressing the “time out” button 72 on the userinterface 60. The “time out” program 138 can be used to clean theaquatic application and/or to perform maintenance procedures.

In the priming category 118, the priming of the pool pump 10 can beenabled or disabled. If the priming is enabled, a duration for thepriming sequence can be programmed into the on-board controller 16. Insome embodiments, the priming sequence can be run at the maximum speed126. The priming sequence can remove substantially all air in order toallow water to flow through the pool pump 10 and/or connected pipingsystems.

In some embodiments, a temperature sensor (not shown) can be connectedto the on-board controller 16 in order to provide an anti-freezeoperation for the pumping system and the pool pump 10. In theanti-freeze category 120, a speed setting 144 and a temperature setting146 at which the pool pump 10 can be activated to prevent water fromfreezing in the pumping system can be programmed into the on-boardcontroller 16. If the temperature sensor detects a temperature lowerthan the temperature setting 146, the pool pump 10 can be operatedaccording to the speed setting 144. However, the anti-freeze operationcan also be disabled.

FIG. 5A-5C illustrate power consumption curves associated with the motorshaft 56 of the pool pump 10. The power consumption of the motor that isnecessary to pump water and overcome losses will be referred to hereinand in the appended claims as any one of “power consumption curves,”“power consumption values,” or simply “power consumption.” FIG. 5Aillustrates power consumption curves for the motor shaft 56 when theinlet 18 is obstructed at a particular time 200. FIG. 5A illustrates anactual power consumption curve 202, a current power consumption curve204, and a lagged power consumption curve 206. The actual powerconsumption 202 can be evaluated by the on-board controller 16 during acertain time interval (e.g., about 20 milliseconds).

In some embodiments, the on-board controller 16 can filter the actualpower consumption 202 using a fast low-pass filter to obtain the currentpower consumption 204. The current power consumption 204 can representthe actual power consumption 202; however, the current power consumption204 can be substantially smoother than the actual power consumption 202.This type of signal filtering can result in “fast detection” (alsoreferred to as “dynamic detection”) of any obstructions in the pumpingsystem (e.g., based on dynamic behavior of the shaft power when theinlet 18 is blocked suddenly). In some embodiments, the fast low-passfilter can have a time constant of about 200 milliseconds.

In some embodiments, the on-board controller 16 can filter the signalfor the actual power consumption 202 using a slow low-pass filter toobtain the lagged power consumption 206. The lagged power consumption206 can represent the actual power consumption from an earlier timeperiod. If the inlet 18 is obstructed at the time instance 200, theactual power consumption 202 will rapidly drop. The current powerconsumption 204 can substantially follow the drop of the actual powerconsumption 202. However, the lagged power consumption 206 will dropsubstantially slower than the actual power consumption 202. As a result,the lagged power consumption 206 will generally be higher than theactual power consumption 202. This type of signal filtering can resultin “slow detection” (also referred to as “dead head detection” or“static detection”) of any obstructions in the pumping system (e.g.,when there is an obstruction in the pumping system and the pool pump 10runs dry for a few seconds). In some embodiments, the slow low-passfilter can have a time constant of about 1400 milliseconds.

The signal filtering of the actual power consumption 202 can beperformed over a time interval of about 2.5 seconds, resulting in areaction time between about 2.5 seconds and about 5 seconds, dependingon when the dead head condition occurs during the signal filteringcycle. In some embodiments, the static detection can have a 50%sensitivity which can be defined as the power consumption curvecalculated from a minimum measured power plus a 5% power offset at allspeeds from about 1500 RPM to about 3450 RPM. When the sensitivity isset to 0%, the static detection can be disabled.

FIG. 5B illustrates a relative power consumption curve 208 of the poolpump 10 for the same scenario of FIG. 5A. In some embodiments, therelative power consumption 208 can be computed by calculating thedifference between the current power consumption 204 and the laggedpower consumption 206 (i.e., the “absolute power variation”) divided bythe current power consumption 204. The greater the difference betweenthe time constants of the fast and slow filters, the higher the timeframe for which absolute power variation can be calculated. In someembodiments, the absolute power variation can be updated about every 20milliseconds for dynamic detection of obstructions in the pumpingsystem. Due to the lagged power consumption 206 being higher than thecurrent power consumption 204, a negative relative power consumption 208can be used by the SVRS of the on-board controller 16 to identify anobstructed inlet 18.

The relative power consumption 208 can also be used to determine a“relative power variation” (also referred to as a “power variationpercentage”). The relative power variation can be calculated bysubtracting the lagged power consumption 206 from the current powerconsumption 204 and dividing by the lagged power consumption 206. Whenthe inlet 18 is blocked, the relative power variation will be negativeas shaft power decreases rapidly in time. A negative threshold can beset for the relative power variation. If the relative power variationexceeds the negative threshold, the SVRS can identify an obstructedinlet 18 and shut down the pool pump 10 substantially immediately. Inone embodiment, the negative threshold for the relative power variationcan be provided for a speed of about 2200 RPM and can be provided as apercentage multiplied by ten for increased resolution. The negativethreshold for other speeds can be calculated by assuming a second ordercurve variation and by multiplying the percentage at 800 RPM by six andby multiplying the percentage at 3450 RPM by two. In some embodiments,the sensitivity of the SVRS can be altered by changing the percentagesor the multiplication factors.

In some embodiments, the on-board controller 16 can include a dynamiccounter. In one embodiment, a dynamic counter value 210 can be increasedby one value if the absolute power variation is negative. The dynamiccounter value 210 can be decreased by one value if the absolute powervariation is positive. In some embodiments, if the dynamic counter value210 is higher than a threshold (e.g., a value of about 15 so that thecounter needs to exceed 15 to trigger an obstructed inlet alarm), adynamic suction blockage is detected and the pool pump 10 is shut downsubstantially immediately. The dynamic counter value 210 can be anynumber equal to or greater than zero. For example, the dynamic countervalue 210 may remain at zero indefinitely if the shaft power continuesto increase for an extended time period. However, in the case of asudden inlet blockage, the dynamic counter value 210 will rapidlyincrease, and once it increases beyond the threshold value of 15, thepool pump 10 will be shut down substantially immediately. In someembodiments, the threshold for the dynamic counter value 210 can dependon the speed of the motor 14 (i.e., the thresholds will follow a curveof threshold versus motor speed). In one embodiment, the dynamicdetection can monitor shaft power variation over about one second at a20 millisecond sampling time to provide fast control and monitoring.FIG. 5C illustrates the dynamic counter value 210 of the dynamic counterfor the relative power consumption 208 of FIG. 5B.

In one embodiment, the SVRS can determine that there is an obstructedinlet 18 when both of the following events occur: (1) the relative powervariation exceeds a negative threshold; and (2) the dynamic countervalue 210 exceeds a positive threshold (e.g., a value of 15). When bothof these events occur, the on-board controller 16 can shut down the poolpump 10 substantially immediately. However, in some embodiments, one ofthese thresholds can be disabled. The relative power variation thresholdcan be disabled if the relative power variation threshold needs only tobe negative to trigger the obstructed inlet alarm. Conversely, thedynamic counter can be disabled if the dynamic counter value needs onlyto be positive to trigger the obstructed inlet alarm.

The on-board controller 16 can evaluate the relative power consumption208 in a certain time interval. The on-board controller 16 can adjustthe dynamic counter value 210 of the dynamic counter for each timeinterval. In some embodiments, the time interval can be about 20milliseconds. In some embodiments, the on-board controller 16 cantrigger the SVRS based on one or both of the relative power consumption208 and the dynamic counter value 210 of the relative counter. Thevalues for the relative power consumption 208 and the dynamic countervalue 210 when the on-board controller 16 triggers the SVRS can beprogrammed into the on-board controller 16.

FIG. 6 illustrates a maximum power consumption curve 212 and a minimumpower consumption curve 214 versus the speed of the pool pump 10according to one embodiment of the invention. In some embodiments, themaximum power consumption curve 212 and/or the minimum power consumptioncurve 214 can be empirically determined and programmed into the on-boardcontroller 16. The maximum power consumption curve 212 and the minimumpower consumption curve 214 can vary depending on the size of the pipingsystem coupled to the pool pump 10 and/or the size of the aquaticapplications. In some embodiments, the minimum power consumption curve214 can be defined as about half the maximum power consumption curve212.

FIG. 6 also illustrates several intermediate power curves 216. Themaximum power consumption curve 212 can be scaled with different factorsto generate the intermediate power curves 216. The intermediate powercurve 216 resulting from dividing the maximum power consumption curve212 in half can be substantially the same as the minimum powerconsumption curve 214. The scaling factor for the maximum powerconsumption 212 can be programmed into the on-board controller 16. Oneor more of the maximum power consumption 212 and the intermediate powercurves 216 can be used as a threshold value to detect an obstructedinlet 18. In some embodiments, the on-board controller 16 can triggerthe SVRS if one or both of the actual power consumption 202 and thecurrent power consumption 204 are below the threshold value.

In some embodiments, the on-board controller 16 can include an absolutecounter. If the actual power consumption 202 and/or the current powerconsumption 204 is below the threshold value, a value of the absolutecounter can be increased. A lower limit for the absolute counter can beset to zero. In some embodiments, the absolute counter can be used totrigger the SVRS. The threshold value for the absolute counter beforethe SVRS is activated can be programmed into the on-board controller 16.In some embodiments, if the absolute counter value is higher than athreshold (e.g., a value of about 10 so that the counter needs to exceed10 to trigger an obstructed inlet alarm), a dead head obstruction isdetected and the pool pump 10 is shut down substantially immediately. Inother words, if the actual power consumption 202 stays below a thresholdpower curve (as described below) for 10 times in a row, the absolutecounter will reach the threshold value of 10 and the obstructed inletalarm can be triggered for a dead head condition.

For use with the absolute counter, the threshold value for the actualpower consumption 202 can be a threshold power curve with a sensitivityhaving a percentage multiplied by ten. For example, a value of 500 canmean 50% sensitivity and can correspond to the measured minimum powercurve calculated using second order approximation. A value of 1000 canmean 100% sensitivity and can correspond to doubling the minimum powercurve. In some embodiments, the absolute counter can be disabled bysetting the threshold value for the actual power consumption 202 tozero. The sensitivity in most applications can be above 50% in order todetect a dead head obstruction within an acceptable time period. Thesensitivity in typical pool and spa applications can be about 65%.

In some embodiments, the SVRS based on the absolute counter can detectan obstructed inlet 18 when the pool pump 10 is being started against analready blocked inlet 18 or in the event of a slow clogging of the inlet18. The sensitivity of the SVRS can be adjusted by the scaling factorfor the maximum power consumption 212 and/or the value of the absolutecounter. In some embodiments, the absolute counter can be used as anindicator for replacing and/or cleaning the strainer 42 and/or otherfilters installed in the piping system of the aquatic applications.

In some embodiments, the dynamic counter and/or the absolute counter canreduce the number of nuisance trips of the SVRS. The dynamic counterand/or the absolute counter can reduce the number of times the SVRSaccidently shuts down the pool pump 10 without the inlet 18 actuallybeing obstructed. A change in flow rate through the pool pump 10 canresult in variations in the absolute power consumption 202 and/or therelative power consumption 208 that can be high enough to trigger theSVRS. For example, if a swimmer jumps into the pool, waves can changethe flow rate through the pool pump 10 which can trigger the SVRS,although no blockage actually occurs. In some embodiments, the relativecounter and/or the absolute counter can prevent the on-board controller16 from triggering the SVRS if the on-board controller 16 changes thespeed of the motor 14. In some embodiments, the controller 16 can storewhether the type of obstructed inlet was a dynamic blocked inlet or adead head obstructed inlet.

The actual power consumption 202 varies with the speed of the motor 14.However, the relative power consumption 208 can be substantiallyindependent of the actual power consumption 202. As a result, the powerconsumption parameter of the motor shaft 56 by itself can be sufficientfor the SVRS to detect an obstructed inlet 18 over a wide range ofspeeds of the motor 14. In some embodiments, the power consumptionparameter can be used for all speeds of the motor 14 between the minimumspeed setting 124 and the maximum speed setting 126. In someembodiments, the power consumption values can be scaled by a factor toadjust a sensitivity of the SVRS. A technician can program the powerconsumption parameter and the scaling factor into the on-boardcontroller 16.

FIG. 7 illustrates a pool or spa 300 with a vessel 302, an outlet pipe304, an inlet pipe 306, and a filter system 308 coupled to the pool pump10. The vessel 302 can include an outlet 310 and an inlet 312. Theoutlet pipe 304 can couple the outlet 310 with the inlet 18 of the poolpump 10. The inlet pipe 306 can couple the outlet 20 of the pool pump 10with the inlet 312 of the vessel 302. The inlet pipe 306 can be coupledto the filter system 308.

An object in the vessel 302, for example a person 314 or a foreignobject, may accidently obstruct the outlet 310 or the inlet 18 maybecome obstructed over time. The on-board controller 16 can detect theblocked inlet 18 of the pool pump 10 based on one or more of the actualpower consumption 202, the current power consumption 204, the relativepower consumption 208, the dynamic counter, and the absolute counter. Insome embodiments, the on-board controller 16 can trigger the SVRS basedon the most sensitive (e.g., the earliest detected) parameter. Once anobstructed inlet 18 has been detected, the SVRS can shut down the poolpump 10 substantially immediately. The on-board controller 16 canilluminate an LED 96 on the user interface 60 and/or can activate anaudible alarm. In some embodiments, the on-board controller 16 canrestart the pool pump 10 automatically after the time period for theSVRS automatic restart 128 has elapsed. In some embodiments, theon-board controller 16 can delay the activation of the SVRS during startup of the pool pump 10. In some embodiments, the delay can be about twoseconds.

If the inlet 18 is still obstructed when the pool pump 10 is restarted,the SVRS will be triggered again. Due to the pool pump 10 being startedagainst an obstructed inlet 18, the relative power consumption 208 maybe inconclusive to trigger the SVRS. However, the on-board controller 16can use the actual power consumption 202 and/or the current powerconsumption 204 to trigger the SVRS. In some embodiments, the SVRS canbe triggered based on both the relative power consumption 208 and theactual power consumption 202.

In some embodiments, the SVRS can be triggered for reasons other thanthe inlet 18 of the pool pump 10 being obstructed. For example, theon-board controller 16 can activate the SVRS if one or more of theactual power consumption 202, the current power consumption 204, and therelative power consumption 208 of the pool pump 10 varies beyond anacceptable range for any reason. In some embodiments, an obstructedoutlet 20 of the pool pump 10 can trigger the SVRS. In some embodiments,the outlet 20 may be obstructed anywhere along the inlet pipe 306 and/orin the inlet 312 of the pool or spa 300. For example, the outlet 20could be obstructed by an increasingly-clogged strainer 42 and/or filtersystem 308.

In some embodiments, the number of restarts of the pool pump 10 aftertime period for the SVRS automatic restart 128 has been elapsed can belimited in order to prevent excessive cycling of the pool pump 10. Forexample, if the filter system 308 is clogged, the clogged filter system308 may trigger the SVRS every time the pool pump 10 is restarted by theon-board controller 16. After a certain amount of failed restarts, theon-board controller 16 can be programmed to stop restarting the poolpump 10. The user interface 60 can also indicate the error on thedisplay 62. In some embodiments, the user interface 60 can display asuggestion to replace and/or check the strainer 42 and/or the filtersystem 308 on the display 62.

It will be appreciated by those skilled in the art that while theinvention has been described above in connection with particularembodiments and examples, the invention is not necessarily so limited,and that numerous other embodiments, examples, uses, modifications anddepartures from the embodiments, examples and uses are intended to beencompassed by the claims attached hereto. The entire disclosure of eachpatent and publication cited herein is incorporated by reference, as ifeach such patent or publication were individually incorporated byreference herein. Various features and advantages of the invention areset forth in the following claims.

The invention claimed is:
 1. A method of operating a safety vacuumrelease system with a controller for a pump including a variable speedmotor, the method comprising: measuring an actual power consumption ofthe motor necessary to pump water and overcome losses; filtering theactual power consumption with a fast low-pass filter to obtain a currentpower consumption; incrementing an absolute counter value if at leastone of the actual power consumption and the current power consumption isgreater than a threshold power curve; identifying a dead head conditionif the absolute counter value exceeds an absolute counter thresholdvalue; and triggering the safety vacuum release system when the deadhead condition is identified in order to shut down the pumpsubstantially immediately.
 2. The method of claim 1 and furthercomprising: calculating an absolute power variation based on the actualpower consumption; incrementing a dynamic counter value if the absolutepower variation is negative; calculating a relative power variationbased on the actual power consumption; identifying a dynamic suctionblockage if at least one of the dynamic counter exceeds a dynamiccounter threshold value and the relative power variation is below anegative threshold.
 3. The method of claim 2 and further comprising:filtering the actual power consumption with a slow low-pass filter toobtain a lagged power consumption; and calculating the absolute powervariation by subtracting the lagged power consumption from the currentpower consumption.
 4. The method of claim 3 wherein the fast low-passfilter has a time constant of about 200 milliseconds and the slowlow-pass filter has a time constant of about 1400 milliseconds.
 5. Themethod of claim 3 wherein the actual power consumption is filtered forabout 2.5 seconds.
 6. The method of claim 3 wherein the absolute powervariation is updated about every 20 milliseconds to provide dynamicsuction blockage detection.
 7. The method of claim 3 and furthercomprising calculating a relative power consumption by dividing theabsolute power variation by the current power consumption.
 8. The methodof claim 1 wherein the absolute counter threshold value is
 10. 9. Themethod of claim 1 and further comprising restarting the pump after atime period has elapsed.
 10. The method of claim 1 and furthercomprising preventing the pump from being restarted if the dead headcondition is identified again.
 11. The method of claim 2 wherein thedynamic counter threshold value is 15.